2 layers60 × 50 mm
MembraneKeyboard
davidmpye/snackbot
Code, PCB design and 3d printed bits to convert our vending machine to a Pi-based solution
16 parts2GPL-3.0
2 layers85 × 90 mm
Code, PCB design and 3d printed bits to convert our vending machine to a Pi-based solution
- Size
- 85 × 90 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 88
- Nets
- 70
- Pads
- 316
- Tracks, vias
- 614, 105
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 24 Dec 2024
- Updated
- 7 Nov 2026
Overview
Vmc is an open-source printed circuit board by davidmpye, from the davidmpye/snackbot repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 85 × 90 mm with 88 parts on 70 nets, routed with 614 tracks and 105 vias.
It is built around the 74LS14PC, BSS138 and MMBT3906, with the BC817 and GBU6K among its other parts. Its parts include 41 resistors, 17 transistors, 14 connectors, 5 diodes and 3 capacitors. It belongs with the RP2040 boards of this library.
Main components
5
74LS14PC
PDIP-14InvertersTexas Instruments
BSS138
SOT-23-55℃~+150℃ 1 N-channel 1.1Ω@10V、1.2Ω@4.5V 1.2V 1.7nC@10V 17.5pF 340mA 350mW 50V 6.5pF N-Channel SOT-23 MOSFETs ROHShongjiachengMOSFETsMMBT3906
SOT-23-55℃~+150℃ 1 PNP 100 100nA 200mA 200mW 300MHz 300mV 40V 5V PNP SOT-23 Bipolar (BJT) ROHSTWGMCBipolar (BJT)BC817
SOT-231 NPN 100nA 150MHz 300mW 40 45V 500mA 5V 700mV NPN SOT-23 Bipolar (BJT) ROHSShikuesBipolar (BJT)
GBU6K
GBU-55℃~+150℃ 10uA@800V 175A 1V@6A 6A 800V Single-Phase Rectifier GBU Bridge Rectifiers ROHSLGEBridge Rectifiers
README
README.mdSnackbot is Makerspace's vending machine
It was a Polyvend vending machine, but is now a bit of a hybrid of Raspberry Pi and Pico microcontrollers.
More information (and pictures!) to follow!
Parts
88| Qty | Value | Footprint | References |
|---|---|---|---|
| 29 | 10K | Resistor_SMD:R_1206_3216Metric | R1, R2, R10, R11, R12, R13, R14, R15, R16, R17, R18, R19, R20, R21, R22, R23 +13 |
| 14 | BSS138 | Package_TO_SOT_SMD:SOT-23 | Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q16 |
| 4 | LED | LED_SMD:LED_1206_3216Metric_Pad1.42x1.75mm_HandSolder | D1, D3, D4, D5 |
| 3 | 5.1R | Resistor_SMD:R_1206_3216Metric | R39, R40, R41 |
| 3 | R | Resistor_SMD:R_1206_3216Metric | R27, R33, R34 |
| 2 | Conn_01x02 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J7, J8 |
| 2 | MMBT3906 | Package_TO_SOT_SMD:SOT-23 | Q15, Q17 |
| 1 | 1.4K | Resistor_SMD:R_1206_3216Metric | R38 |
| 1 | 1000uF 50V | Capacitor_THT:CP_Radial_D12.5mm_P5.00mm | C2 |
| 1 | 24VAC | Connector_JST:JST_VH_B3P-VH-B_1x03_P3.96mm_Vertical | J3 |
| 1 | 24VDC | Connector_JST:JST_VH_B2P-VH_1x02_P3.96mm_Vertical | J6 |
| 1 | 330uF 50V | Capacitor_THT:CP_Radial_D10.0mm_P5.00mm | C3 |
| 1 | 470R | Resistor_SMD:R_1206_3216Metric | R28 |
| 1 | 4k7 | Resistor_SMD:R_1206_3216Metric | R31 |
| 1 | 5R | Resistor_SMD:R_1206_3216Metric | R29 |
| 1 | 74LS14 | Package_SO:SOIC-14_3.9x8.7mm_P1.27mm | U2 |
| 1 | 750R | Resistor_SMD:R_1206_3216Metric | R37 |
| 1 | AUX_1 | Connector_JST:JST_PH_B3B-PH-K_1x03_P2.00mm_Vertical | J12 |
| 1 | AUX_2 | Connector_JST:JST_PH_B3B-PH-K_1x03_P2.00mm_Vertical | J13 |
| 1 | AUX_3 | Connector_JST:JST_PH_B3B-PH-K_1x03_P2.00mm_Vertical | J14 |
| 1 | BC817 | Package_TO_SOT_SMD:SOT-23 | Q14 |
| 1 | C | Capacitor_SMD:C_1206_3216Metric | C1 |
| 1 | Conn_01x02_Pin | Connector_JST:JST_PH_B2B-PH-K_1x02_P2.00mm_Vertical | J2 |
| 1 | Conn_02x08_Odd_Even | Connector_PinHeader_2.54mm:PinHeader_2x08_P2.54mm_Vertical | J1 |
| 1 | GBU6K | Diode_THT:Diode_Bridge_Vishay_GBU | D2 |
| 1 | I2C header | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J5 |
| 1 | MDB_CONN | Connector_Molex:Molex_Mini-Fit_Jr_5566-06A_2x03_P4.20mm_Vertical | J4 |
| 1 | ONE_WIRE_1 | Connector_JST:JST_PH_B3B-PH-K_1x03_P2.00mm_Vertical | J10 |
| 1 | ONE_WIRE_2 | Connector_JST:JST_PH_B3B-PH-K_1x03_P2.00mm_Vertical | J11 |
| 1 | PICO_DEBUG_HEADER | Connector_PinSocket_2.54mm:PinSocket_1x03_P2.54mm_Vertical | J9 |
| 1 | Pico | Pi:RPi_Pico_SMD_TH | U1 |
| 1 | Polyfuse | footprints:FUS_RKEF300_TYCO_TYC | F1 |
| 1 | R470 | Resistor_SMD:R_1206_3216Metric | R35 |
The 83 most common of 88 parts.
Questions
How big is the Vmc PCB?
It measures 85 × 90 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Vmc use?
88 parts, built around the 74LS14PC, BSS138, MMBT3906 and BC817. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Vmc KiCad files?
From the davidmpye/snackbot repository on GitHub, at the commit this page was made from: the board is vmc/pcb/pcb.kicad_pcb and its schematic matrix-keyboard/pcb/MembraneKeyboard.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Vmc design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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